I took a class called “3 Simple Finishes” a couple of years ago, and though this was not one of the 3 covered in the title, it was mentioned in passing. When you mix vinegar (I used apple cider vinegar) and throw in some fine steel wool, it makes a kind of black stain for wood. Just paint it on. and let it set overnight.

Top left: tung oil on cedar
Top right: vinegar stain
Bottom left: more oil, 2 coats’ worth
Bottom right: vinegar stain, then oil
I tried this technique out on a cedar wall piece that also uses my homemade circle-cutting router jig.

The square field has been dyed, then oiled. I then used the router jig and a v-groove bit to cut concentric rings in the wood. This removed the dyed area. Then, I oiled the whole piece again. I actually think it would have looked better with no oil, and perhaps a less-red wood. Still, the cedar was from some dimensional lumber scraps I had around, so the price for this experiement was right. I do like this concentric idea a lot, though. Like growth rings on a tree, but still kind of graphic and vaguely primitive and aged-looking.
I think I might try burning the surface of the next one to a good char and skipping the oil on the newly exposed wood.
It’s 25 inches square.